1. Field of the Invention
The present invention relates generally to an improvement in a magnetic recording device such as a magnetic disk drive and a magnetic tape drive, and more particularly to a magnetic head suitable for high-speed data transfer, a manufacturing method for the magnetic head, and a magnetic recording device having such a magnetic head.
In recent years, a data transfer rates have been increased with increases in recording density in magnetic recording devices. In response thereto, a magnetic head capable of recording data on a recording medium with a high-frequency signal is required.
2. Description of the Related Art
One type of conventionally known magnetic recording device includes a magnetic recording medium having a recording surface and a magnetic head to be accessed to an arbitrary position on the recording surface. A magnetic disk drive that includes a magnetic disk which is rotatably driven, and a magnetic head mounted on a head slider flying above the magnetic disk is one example of such a recording device. The head slider is driven in the radial direction of the magnetic disk by a head actuator that includes a voice coil motor, thereby accessing the magnetic head to an arbitrary position on the recording surface of the magnetic disk.
In this specification, the term of "magnetic recording" is used in the sense of magnetic writing and/or reading of electrical data.
One type of conventionally known magnetic head that is applicable to a magnetic recording device is an inductive magnetic head, which generally includes a magnetic pole piece for forming a recording gap (magnetic gap for writing/reading) and a coil interlinked with the magnetic pole piece. By passing a current modulated by data through the coil when writing data, a magnetic field that varies with the modulated current is formed in the recording gap. Accordingly, data is written on the recording surface of a recording medium by displacing the magnetic head relative to the recording medium in the condition where the magnetic head is opposed to the recording surface of the recording medium. On the other hand, when reading data recorded on a recording medium, the magnetic head is displaced relative to the recording medium to form a change in magnetic flux in a magnetic circuit including the magnetic pole piece and the recording surface of the recording medium, causing a change in voltage between the opposite ends of the coil, thereby reading data.
In recent years, a magnetoresistive effect element (MR element) whose resistance changes according to the magnitude of a magnetic field has been developed for reading only. A composite magnetic head including an MR element and an inductive magnetic head as a unit is usually called an MR head. In the MR head, the inductive magnetic head is used for writing only.
A conventional manufacturing method for the inductive magnetic head includes the step of obtaining a magnetic pole piece by precipitating a substantially uniform soft magnetic layer by electroplating. The soft magnetic layer is formed of a soft magnetic material such as permalloy. Permalloy is an alloy of 80 to 82% Ni (nickel) and the remaining percentage of Fe (iron).
With an increase in modulation frequency in writing data on a recording medium, the effect of eddy-current loss in the magnetic pole piece becomes large. That is, the head's writing ability to the recording medium decreases because of a reduction in the magnetic field strength while writing data in a high-frequency region.
In this respect, development is being pursued of a material having a high resistivity to accordingly achieve a reduced eddy-current loss, a material having a high saturation magnetic flux density to accordingly achieve a high magnetic field strength, or a material having a high resistivity and a high saturation magnetic flux density. However, in the case of using an electroplating method to provide the magnetic pole piece of the magnetic head, it is difficult to apply a material having a high resistivity or a material having a high saturation magnetic flux density.
It can be proposed to manufacture a magnetic pole piece of a material having a high resistivity or a material having a high saturation magnetic flux density by film deposition by sputtering and thereafter dry etching the deposited film. In this case, however, it is very difficult to accurately manufacture the front end of the magnetic pole piece to be of a narrow width. In other words, a high recording density to a magnetic recording medium cannot be obtained by the combination of sputtering and dry etching.